It has been conventional practice to produce mineral fibers, and particularly glass fibers, through electrically heated bushings. It is necessary to distribute the heat pattern of the bottom wall of the bushing as uniformly as possible for a successful fiber forming operation. Controlling the electrical flow through the bushing to control the heat pattern has generally been done by varying the size of the end walls of the bushing and by the configuration and location of the electrical terminals. Such bushing arrangements produce within the bushings current paths which basically travel through the base plate initially and then spread into the sidewalls to produce a heat pattern with higher temperatures in the center end region of the bushing near the terminal and lower temperatures in corners of the bottom wall. With the advent of larger bushings, and particularly wider bushings, it has become progressively difficult to supply sufficient heat to the corner regions of the bushing and to maintain a desired temperature in the central region of the bottom wall.